Tuesday, June 13, 2006

Pharyngula has an interesting response to an interview with a biologist about homosexuality and evolution. There's a lot of discussion about where homosexuality comes from. I have my own ideas, and I'm sure we all do, but this bit I found particularly interesting:

Homosexuality is a byproduct. This is my favorite explanation, because ultimately it's about development. Why do men have nipples? Because women need them. Both men and women have the same set of genes (more or less), and follow very similar developmental pathways, and the nipple represents a developmental constraint or byproduct: mutations that knock out the male nipple might also knock out the female nipple, so the structure is retained in both sexes. Male nipples are a byproduct of a function needed by the other sex.

We might also ask, why do some men love other men? The answer: because women need to love men. (We could also propose the complement, that lesbians exist because men need to love women.) If there are pathways that can predispose an individual to find males sexually attractive, the base structure is present in both men and women, and what we have are additional mechanisms to modulate the expression of the trait in men vs. women. Just as we guys have an echo of a female attribute in our nipples, why not assume that we also bear echoes of female mate preferences in our brains—echoes that can't be expunged without also eliminating women's desire for men (and oh, no, we mustn't have that, I know)?

That is one way of looking at it that I had just never considered before.